Page 96 - The Creation Of The Universe

Many completely different factors such as the distance between Earth and Sun, the planet's rotation-
al speed, the inclination of its axes, and the geographical features of the surface all combine to ensure
that our world is heated in just the right way that life needs and that this heat is adequately distrib-
uted.
the light and dark sides of the planet are quite modest. The importance of
this can be seen in the extreme example of Mercury, where a day lasts
longer than a year and where the difference between daytime and night-
time temperatures is almost 1,000°C.

Geography also helps distribute heat equally over the earth. There is a
difference of about 100°C between the polar and equatorial regions of
Earth. If such a thermal gradient were to exist over a completely level area,
the result would be winds reaching speeds as high as 1,000 kilometers an
hour sweeping away everything in their path. Instead, Earth is full of geo-
graphical barriers that block the huge movements of air that such a thermal